1. Field of the Invention
The present invention relates to a sheet feeding apparatus and a medium detecting method, and, more particularly to a sheet feeding apparatus and a medium detecting method that can be suitably applied to a sheet feeding apparatus capable of separating each sheet-like medium from plural sheet media and feeding each separated sheet-like medium.
2. Description of the Related Art
Conventional sheet feeding apparatuses are incorporated in an apparatus that handles paper sheets as plural-sheet media, such as an image reading apparatus like an image scanner, a copying machine, a facsimile machine, and a character recognition apparatus. The sheet feeding apparatus separates each sheet from stacked sheets, and feeds each separated sheet to the image reading apparatus. With this arrangement, even when plural sheets are stacked, each sheet can be automatically fed to the image reading apparatus, and the image reading apparatus fed with each sheet-like medium can process each sheet.
According to such a sheet feeding apparatus, when plural sheets are bound by a staple or the like, although a part of the sheets bound by the staple is fixed to other sheets, each sheet is fed and separated. Therefore, there is a risk that the sheets are rotated around a stapled portion, and the sheets and the apparatus are damaged. Consequently, according to the conventional sheet feeding apparatus, when a stapled original as a medium having plural sheets bound by a staple is detected, the sheet feeding apparatus stops feeding, thereby preventing the sheets and the apparatus from being damaged.
As a technique of detecting such a stapled original, for example, Japanese Patent Application Laid-open No. 2007-150909 discloses an original feeding apparatus that detects a stapled original from a result of detecting oscillation or acceleration of a contact member arranged contactably to an original being conveyed.
According to the above conventional sheet feeding apparatus, when a sheet is erroneously detected as a stapled original, feeding thereof is stopped, and there is a risk of decreasing the operation efficiency as a result. Accordingly, more accurate detection of a stapled original has been desired.